It is intended to investigate experimentally (in rhesus monkeys) and pathologically retinal, optic nerve head, and uveal vascular disorders. In (a) ischemic, (b) hemorrhagic, and (c) venous stasis retinopathy, it is our intention to study (1) the time required for the retinal ischemia to produce functional and anatomical deaths in the retina and its various components, and various factors influencing this; (2) the natural history, pathology and pathogenesis of various retinal vascular diseases in a detailed prospective experimental study; and (3) the evolution of the retinal vascular dynamics. The uveal circulation in health and disease will be investigated systematically to determine the ocular lesions produced by occlusion of various ciliary vessels, and the role of the posterior ciliary ischemia in glaucoma, low-tension glaucoma, and other optic disc ischemic disorders. In all these studies, the assessment will be made (1) for the various ocular lesions, (2) for the circulatory dynamics by perfusion and fluorescein angiography, (3) for retinal functions by electrophysiological testing, and (4) for pathological changes by histological and electron microscopical examination.